1. Field of the Invention
The present invention relates to hearing aids. The invention further relates to a method for guiding a hearing aid user in the insertion of an ear plug.
In the context of the present disclosure, a hearing aid should be understood as a small, microelectronic device designed to be worn behind or in a human ear of a hearing-impaired user. The hearing aid is adjusted by a hearing aid fitter according to a prescription. The prescription is based on a hearing test, resulting in a so-called audiogram, of the performance of the hearing-impaired user's unaided hearing. The prescription is developed to reach a setting where the hearing aid will alleviate a hearing loss by amplifying sound at frequencies in those parts of the audible frequency range where the user suffers a hearing deficit. A hearing aid comprises one or more microphones, a microelectronic circuit comprising a signal processor, and an acoustic output transducer, in hearing aid parlance referred to as a “receiver”.
A Behind-The-Ear (BTE) hearing aid is worn behind the ear, and has a housing comprising the major electronics parts behind the ear and an earpiece, sometimes called an ear plug, for emitting sound to the ear canal of the hearing aid user. The ear plug is worn in the ear, e.g. in the concha or the ear canal. In a traditional BTE hearing aid, a sound tube is used for conducting sound from a loudspeaker or receiver in the housing to the ear plug. In some types of hearing aids the receiver is arranged in the ear plug and is connected through electrical conductors to the housing behind the ear. Such hearing aids are commonly referred to as Receiver-In-The-Ear (RITE) hearing aids.
Often the receiver is placed inside the ear canal. This may be referred to as Receiver-In-Canal (RIC) hearing aids.
In-The-Ear (ITE) hearing aids are designed for arrangement in the ear, normally in the funnel-shaped outer part of the ear canal. Often the hearing aid is placed substantially inside the ear canal. This may be referred to as Completely-In-Canal (CIC) hearing aids. This type of hearing aid requires a very compact design in order to allow it to be arranged in the ear canal, while accommodating the components necessary for operation of the hearing aid, such as microphones, a microelectronic circuit comprising a signal processor, an acoustic output transducer and a battery.
Hearing aids or ear plugs of hearing aids are made to fit tightly in the ear canal of the hearing aid user in order to achieve an optimum sound amplification without risk of feedback. The receiver delivers sound into the inner part of the ear canal delimited by the ear plug or hearing aid.
Any need for air ventilation into the inner part of the ear canal is taken care of by a well controlled ventilation channel, often referred to as a vent. A ventilation channel also has the advantage of reducing any occlusion effect (see explanation in WO-A1-2010/083888 page 1-3). The ventilation channel usually has a tubular shape, and the diameter is selected as a compromise between the wish to reduce occlusion and the need to obtain a sufficiently high sound pressure level at the ear drum. The ventilation channel (or vent) is an intentional air leak between the air volume in front of the ear drum limited by the ear plug or hearing aid, and the surroundings outside the ear canal.
For hearing aid users it may be difficult to arrange the hearing aid or the hearing aid ear plug correct in the ear canal and to verify that it is correctly placed. Here the term ear plug is used to generally designate whatever part of the hearing aid is arranged in the ear canal. The ear plug may be an ear piece of a behind-the-ear hearing aid, an in-the-ear hearing aid or a completely-in-canal hearing aid. If the ear plug is not correctly placed in the ear canal an unintended air leak between the space in front of the ear drum and the surroundings may be formed. Such an air leak will increase the risk of feedback and it will reduce the sound pressure level produced by the hearing aid at lower frequencies at the ear drum. The benefits of the hearing aid will therefore be reduced.
2. The Prior Art
U.S. 2007/0019817 discloses a hearing aid which by playing an acoustic test signal can measure if the fitting of the ear plug is correct. The test signal measured by a microphone is compared to a reference determined beforehand and stored in the hearing aid. If the test signal detected by the microphone deviates from the reference, information is given to an external unit that the fitting is not correct.
WO 2010/049543 discloses a method of measuring feedback of a hearing aid and, based on a comparison with feedback measured when the ear plug is optimally fitted into the ear canal, deciding if the hearing aid is properly inserted in the ear canal of the hearing aid user.
The problem of these known means for controlling the fitting of a ear plug in the ear canal is, that they can only be applied for measuring if the fitting is correct or not. A more intuitive guidance to the hearing aid user during insertion is not provided.